Conveyor belts are a known means for conveying goods, for example raw materials, semi-finished products or products in a manufacturing environment for foodstuff, for example. In known embodiments, such conveyor belts are composed of one or more layers of material, each layer having different properties which are relevant for the quality and intended use of the conveyor belt. A customary construction for a conveyor belt is a coating layer, for example made from polyurethane, on which one or more reinforcing layers are arranged, for example made from a porous, fibre-like structure made from polyester fabric. The reinforcing layers may in this case be impregnated and the conveyor belt may furthermore be provided with a base layer made from polyurethane. All layers extend over the entire width of the conveyor belt, for example in order to facilitate the production.
A drawback of a conveyor belt constructed in this way is that the reinforcing layers with a porous, fibre-like structure adjoin the edge parts of the conveyor belt. This makes it possible for impurities to penetrate the conveyor belt during use, which is not hygienic and therefore undesirable.
A known solution for eliminating this disadvantage is sealing the edges of the conveyor belt using a non-porous material. U.S. Pat. No. 3,840,424, for example, discloses producing a groove near an intended edge part of the conveyor belt, which groove is then filled with a filler with sealing properties.
In order for the filler to adhere permanently to the groove, the shape of the groove has to be trapezoid or stepped in the transverse direction, as a result of which the reinforcing layers are cut off in a staggered manner when the groove is produced. The groove is usually produced by gouging the conveyor belt with a knife specially provided for this purpose and having a cutting edge with the required trapezium or stepped shape. Knives provided with a trapezium or stepped cutting edge have the drawback that they have to be specially selected, tailored to the conveyor belt to be sealed, for example based on thickness and the position of the reinforcing layers. They also have the disadvantage that they are relatively complicated, expensive and difficult to regrind. In addition, the required cutting forces are considerable.
Due to the desired small remaining thickness at the groove, the conveyor belt is more susceptible to damage by the large cutting forces, as a result of which it is only possible in practice to produce a groove which is not as deep as is desired.
The large cutting forces furthermore require large driving forces to pull the conveyor belt through the machine. In order to be able to generate these large driving forces, large clamping forces are required, which may force the belt out of the desired direction. With known devices, the conveyor belt is passed through the machine by hand. During this procedure, small corrections are carried out by hand in order to ensure that the belt runs through the machine in a straight line. It is very difficult to form a sufficiently straight groove in this way.
Because of the large amount of manual work involved, it is not possible to produce more than one groove at a time in a conveyor belt. In practice, it is usually desirable to seal off several edge parts, so that the conveyor belt has to be passed through twice.